The present invention relates to a device for use in helmets for preventing fogging by electric heating.
When helmets of the full-face type for motorcycle or snowmobile riders are used in a cold climate, the shield panel covering the front opening of the helmet is likely to fog up due to the condensation of water vapor on the inner surface of the panel, or the droplets of water formed by condensation will freeze, consequently obstructing the field of view and rendering the helmet unusable. Stated more specifically, with the helmet which is used on a motorcycle or like vehicle running at a high speed, the shield panel is exceedingly cooled with air during running, so that when the interior of the helmet becomes no longer ventilated on stopping, the heat released from the face of the rider raises the temperature of the interior to produce a difference in temperature between the inside and outside of the helmet, fogging up the inner surface of the shield panel due to the condensation of water vapor and permitting the droplets of water to freeze immediately. Accordingly a device has been provided which comprises a resistance wire attached to the inner surface of the shield panel for maintaining the panel in a heated state by passing current through the wire to prevent freezing. However, the device, which is adapted to heat the shield panel locally, is unable to achieve a sufficient effect to prevent freezing.